jjcirocz

Does anybody know when GM went from the 7.5 to the 7.625. I have a 7.5 rearend and I blew it up and all the spare axles I have are 7.625 and I would not be able to reuse my locker. If I knew the year they changed I can try to find one in the junkyard. Can all 7.625 axles be identified by the extra rib on the passenger side from the axle to the pinion? Also when did GM go to 28 spline? (I forgot) Thank you very much!!!

AlkyIROC

Axles have nothing to do with ring gear size.

GM went from 7-1/2" to 7-5/8" somewhere around 1986. Both sizes fit on the same carrier so even the newer ones are still called 7-1/2" diffs.

The 1990 model year got the 28 spline axles although there may be a few late 1989 cars with them. In 1993 when GM introduced the fourth gen, the axles got longer so the only factory 28 spline axles you can use are from a 90-92 car.

All third gen 10 bolt axles from 1982 to 1989 will interchange into the stock 26 spline carrier reguardless of gear ratio or ring gear size. Left and right axles are also the same length.

jjcirocz

So in 86 they changed the centers? My center has two large openings and the 7.625 have one large opening and a small opening. also the 7.625 is wider where the locker goes. But you are saying that I can Install the gears out of the the7.625 and install them in my 7.5. Also is this a bad idea to reuse gear sets? Thanks

AlkyIROC

In 1986 or so they changed the size of the ring gear. It increased from 7-1/2" to 7-5/8" The carrier, posi or open, didn't change until 1990 when the side gears were upgraded to 28 splines and the hole through the carrier to the side gears was increased slightly to allow 28 spline axles into it.